1. Field of the Invention
This invention relates generally to chemical analysis apparatus, and relates more particularly to an apparatus and method for determining chemical concentration based on waveform distortion analysis.
2. Description of the Relevant Art
The public awareness of the health hazards that sodium compounds including table salt pose in food products has increased dramatically in recent years. There are a number of apparatus currently available that are capable of performing chemical analyses using a variety of techniques to measure concentrations of chemical substances such as sodium. These techniques include mass spectrophotometry, nuclear resonance, flame photometry, specific electrodes, conductivity testers, and refractometry. Unfortunately, the accuracy of these currently available apparatus is strongly dependent upon their cost. At the low end of the cost scale is the continuity tester, which measures the conductivity of a test sample to determine sodium content. Unfortunately, a continuity tester will yield inaccurately high test results when the test sample contains other conductive substances such as vinegar. What is needed is an inexpensive, but accurate, sodium measurement apparatus.
On a broader scale, there is a need for a chemical analysis apparatus that is accurate, easy to use, and inexpensive, and that responds rapidly to changes in chemical concentrations. A fiew of the many approaches to chemical analysis apparatus are described in the following U.S. Pat. Nos.: 3,048,772, issued Aug. 7, 1962 to R. K. Saunders, et al., entitled "Process for Conducting Quantitative Analysis," which discloses a nuclear magnetic resonance spectrometer; 3,287,638, issued Nov. 22, 1966 to V. W. Bolie, entitled "Method of Counting Erythrocytes Utilizing High Frequency Current," which measures the impedance variation of a solution flowing through an orifice to count red blood cells; 3,489,522, issued Jan. 13, 1970 to H. M. McConnell, entitled "Electron Spin Resonance Labeling of Biomolecules," which utilizes a radio frequency alternating magnetic field and a unidirectional magnetic field to identify biomolecules; and 3,765,841, issued Oct. 16, 1973 to Paulson, et al., entitled "Method and Apparatus for Chemical Analysis," which measures the rate of change of the conductivity of a test sample to measure the concentrations of reactive substances. Chemical analysis apparatus such as these are either very expensive, or very limited in their use.